| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Thursday Sessions |
| Session PS-ThM |
| Session: | Plasma Sources |
| Presenter: | Tetsuya Goto, Tohoku University, Japan |
| Authors: | T. Goto, Tohoku University, Japan S.K. Kobayashi, Kotec Company, Ltd., Japan S. Sugawa, Tohoku University, Japan |
| Correspondent: | Click to Email |
Realization of high-quality silicon nitride film formation at low temperature was strongly required for various fields such as the Si CMOS devices, the solar cells, as well as the micro electro mechanical systems (MEMS). In this study, a magnetic-mirror confined electron cyclotron resonance plasma source for low-damage plasma processings was newly developed, and applied to the silicon nitride film formations. The mirror-confined plasma is the well known concept in a field of fusion plasmas where high-density and high-temperature plasmas are produced by confining plasmas using the magnetic field. We applied this concept to plasma enhanced chemical vapor depositions. In a magnetically confined plasma, neutral reactive species produced by the plasma can escape from the confined plasma without the restriction of motion by the magnetic field, contrary to the confined charged particles of ions and electrons. Thus, when the substrate is placed at the neighborhood of the confined plasma, a large amount of reactive species will be supplied to the substrate with low irradiation of ion flux, suggesting the realization of low-damage and high-quality processes. It was found that the magnetic mirror confinement method worked well to excite the high-density plasma larger than 1011 cm-3 with low plasma excitation power of 10 W or less. SiN films were deposited by exciting Ar/SiH4/N2/H2 plasmas. It was found that, in the optimized condition, an impurity concentration of oxygen in the film could be suppressed less than 1%, which was even smaller than that in the controlled low-pressure chemical-vapor deposited film at 750◦C, suggesting the realization of high-quality nitridation process. Next, wet etching stability was investigated by dipping the films into the 5% HF solution. For the 400◦C-deposited film, the etching rate was approximately 3 nm/min which was the same level to that of 750◦C-LPCVD film. Although the etching rate of the 200◦C-deposited film increased to approximately 10 nm/min, this rate was much smaller than that of thermally-grown SiO2 film (approximately 40 nm/min).
It was also confirmed that the excellent step coverage could be obtained for the 0.5 micron trench pattern.
The developed plasma source has a potential to realize high-quality film deposition processes of the plasma CVD, the plasma ALD, and the reactive sputtering.
Acknowledgement
The deposition process was carried out in Fluctuation-Free-Facility in Tohoku University.
1. T. Goto, K. Sato, Y. Yabuta and S. Sugawa, Rev. Sci. Instrum. vol. 87 (2017) 123508.
2. T. Goto, K. Sato, Y. Yabuta, S. Hara and S. Sugawa, Journal of the Electron Devices Society, vol. 6, (2018) 512.